The standard or conventional bicycle construction is well known. It consists of a frame, a steerable wheel at the front of the frame, a driving wheel at the rear of the frame, a seat, handlebars for steering the steerable wheel, and two pedals mounted at either side of the frame between the wheels. The pedals are locked together on a single rotating shaft, and extend in diametrically opposite directions, so that when one pedal is up the other is down. In the simplest form of conventional bicycle, a sprocket wheel is keyed to the shaft turned by the pedals, and a driving chain is entrained around the sprocket and a driven sprocket which is fixed at the hub of the rear wheel to turn therewith.
More recently, 3-speed, 5-speed and 10-speed bicycles have been developed, but all of these utilize the same circular motion for the pedals, which turn one or more drive sprockets keyed to the pedal shaft.
Occasional attempts have been made to devise an alternative pedalling scheme, since it is universally recognized that the circular motion of the pedals in a conventional bicycle represent a substantial inefficiency, since no conversion of downward force to rotational torque can take place when the pedals are at or near the top or bottom dead center positions.
An example of pedals mounted to rotate through a limited arc can be seen in U.S. Pat. No. 2,141,233, issued Dec. 27, 1938 to C. S. Alexander. In the Alexander structure, however, and in any other limited arc pedal construction of which I am aware, there is not provided a simple, safe and reliable means of ensuring that when one pedal moves downwardly the other one moves upwardly.
It is to be emphasized that such positive uplift of the one pedal while the other is depressed is an important factor for the comfort and ease of the person riding the bicycle. To begin with, all standard bicycles have circularly rotating pedals extending at 180.degree. from each other, which automatically ensures that as the one pedal is depressed, the other is raised. Virtually every person who has ever ridden a bicycle has become used to allowing the non-working foot to simply rest on the pedal that is being raised, while the other foot presses downwardly on the working pedal. The procedure then alternates, and the previously working foot rests on its pedal as the latter is being raised.
Without some mechanism or device which ensures that one pedal will be raised as the other is depressed, there is a necessity for providing some resilient means for biasing the pedal in the upward direction. This is a disadvantage in that, when that pedal becomes the working pedal and is pressed downwardly, the rider loses some of his energy to overcoming the resilient biasing means. A more important disadvantage, however, is that the rider may forget to raise his non-working foot as the other is forced downwardly, and thus when it comes time for the non-working foot to become the working foot, the respective pedal is not in the appropriate uppermost position.
It can be seen, therefore, that important advantages would accrue in a structure which firstly employed pedal arms operating over a limited arc (thus avoiding the waste of energy at the top and bottom dead center positions) and which moreover provided a non-resiliently biased but positive "restoring" for the non-working pedal, so that it will be raised to its upper- most position as the working pedal is depressed.
Idealy, the mechanism would be one and the same for both pedals. In other words, the same structure would operate to raise one pedal as the other were depressed, and then would continue to function as the pedals were reversed.